/* 媒介查询，当浏览窗口分辨率发生改变，对应于不同的效果 */
@media screen and (min-width: 1200px) {
    h1 {
        color: skyblue;
    }
}
@media screen and (min-width: 900px) and (max-width:1200px) {
    h1 {
        color: red;
        /* font-size: 20px; */
    }
}
@media screen and (min-width: 100px) and (max-width: 900px) {
    h1 {
        color: green;
        /* font-size: 20px; */
    }
}